assembly-x86

assembly-x86 is a skill for Codex from OutlineDriven/outline-driven-development. It costs 48 tokens per session (1,738 once invoked), scanned A, original, Apache-2.0.

A reference for reading and writing x86-64 assembly, the low-level instructions used by 64-bit Intel and AMD processors. It covers the compiler's AT&T notation and the System V AMD64 rules for passing values between functions.

In plain words
What is it for?
Use it to inspect compiler-generated assembly, write inline assembly in C or C++, decode register and stack usage, and check whether code follows the Linux and macOS function-calling rules.
Why use it?
It helps avoid mistakes when assembly uses the wrong registers, stack layout, or calling convention. It also clarifies whether assembly is compatible with GCC or Clang output.

Skill for Codex

Written for Codex: agents/openai.yaml present. Also seen: positional $N argument.

Good fit Use it to inspect compiler-generated assembly, write inline assembly in C or C++, decode register and stack usage, and check whether code follows the Linux and macOS function-calling rules.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/outlinedriven/outline-driven-development/assembly-x86
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add OutlineDriven/outline-driven-development --skill assembly-x86
Clone the repo
git clone --depth 1 https://github.com/OutlineDriven/outline-driven-development

Made for: Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for assembly-x86

README.md
[![agentmods](https://agentmods.dev/badge/skills/outlinedriven/outline-driven-development/assembly-x86/github.svg)](https://agentmods.dev/skills/outlinedriven/outline-driven-development/assembly-x86)
Your own site
<a href="https://agentmods.dev/skills/outlinedriven/outline-driven-development/assembly-x86"><img src="https://agentmods.dev/badge/skills/outlinedriven/outline-driven-development/assembly-x86/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for assembly-x86

Your own site · 80×15
<a href="https://agentmods.dev/skills/outlinedriven/outline-driven-development/assembly-x86"><img src="https://agentmods.dev/badge/skills/outlinedriven/outline-driven-development/assembly-x86.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 48 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,738 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00048 $0.01738
Opus 5 $0.00024 $0.00869
Sonnet 5 $0.00010 $0.00348
Haiku 4.5 $0.00005 $0.00174

Measured 3d ago against content hash 1422f962b001, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

assembly-x86 scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.devin/skills/assembly-x86/SKILL.md · 124 lines

How it starts

The opening of the file, as written. The whole thing — 124 lines — stays where its author put it; the contents beside it link to each section on GitHub.

x86-64 assembly

GCC and Clang emit AT&T syntax by default. This skill reads that output, writes inline asm, and keeps register use inside the System V AMD64 ABI.

Contract

Field Bound contract
Trigger The task reads compiler assembly output, writes inline asm in C or C++, decides AT&T versus Intel syntax, or explains calling conventions and stack layout in a disassembly.
Authority Read-only. The skill explains and drafts; edits land through the normal coding path. No remote mutation.
Side effect None.
Done The drafted assembly assembles with gcc -c or clang -c, or the compiler output under discussion is explained register by register.

Inputs

  • The C or C++ source, compiler output, or assembly fragment: required.
  • The compiler: required. AT&T versus Intel output and inline asm details follow it.
  • The ABI: required. System V for Linux and macOS; the Microsoft x64 ABI changes the register map entirely.

Procedure

  1. Generate the baseline. Read the compiler's own output before writing any. Done when: the disassembly of the function under discussion is on screen.
gcc -O2 -S -fverbose-asm foo.c -o foo.s
gcc -O2 -c foo.c -o foo.o && objdump -d -M intel foo.o
  1. Map registers by role. Done when: every register in the fragment is classified.
Register 32-bit view Role
rax eax Accumulator, 1st return value, caller saved
rbx ebx Base, callee saved
rcx ecx 4th argument, caller saved
rdx edx 3rd argument, 2nd return value, caller saved
rsi esi 2nd argument, caller saved
rdi edi 1st argument, caller saved
rbp ebp Frame pointer, callee saved
rsp esp Stack pointer
r8 to r11 5th through 8th arguments, caller saved
r12 to r15 Callee saved
rflags flags Condition codes
xmm0 to xmm7 FP and SIMD arguments and returns
xmm8 to xmm15 FP and SIMD scratch, caller saved

Read the full file on GitHub · 124 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 124 lines · 48 tokens per session scan A 1422f962b001

Subscribe to this mod's changes

assembly-x86 is a skill published in the GitHub repository OutlineDriven/outline-driven-development (52 stars, last pushed 3d ago), licensed Apache-2.0. It adds 48 tokens to every session and 1,738 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-06.

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